1 //===-- LiveIntervalAnalysis.cpp - Live Interval Analysis -----------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the LiveInterval analysis pass which is used
11 // by the Linear Scan Register allocator. This pass linearizes the
12 // basic blocks of the function in DFS order and uses the
13 // LiveVariables pass to conservatively compute live intervals for
14 // each virtual and physical register.
16 //===----------------------------------------------------------------------===//
18 #define DEBUG_TYPE "liveintervals"
19 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
20 #include "VirtRegMap.h"
21 #include "llvm/Value.h"
22 #include "llvm/CodeGen/LiveVariables.h"
23 #include "llvm/CodeGen/MachineFrameInfo.h"
24 #include "llvm/CodeGen/MachineInstr.h"
25 #include "llvm/CodeGen/MachineLoopInfo.h"
26 #include "llvm/CodeGen/MachineRegisterInfo.h"
27 #include "llvm/CodeGen/Passes.h"
28 #include "llvm/Target/TargetRegisterInfo.h"
29 #include "llvm/Target/TargetInstrInfo.h"
30 #include "llvm/Target/TargetMachine.h"
31 #include "llvm/Support/CommandLine.h"
32 #include "llvm/Support/Debug.h"
33 #include "llvm/ADT/Statistic.h"
34 #include "llvm/ADT/STLExtras.h"
39 // Hidden options for help debugging.
40 static cl::opt<bool> DisableReMat("disable-rematerialization",
41 cl::init(false), cl::Hidden);
43 static cl::opt<bool> SplitAtBB("split-intervals-at-bb",
44 cl::init(true), cl::Hidden);
45 static cl::opt<int> SplitLimit("split-limit",
46 cl::init(-1), cl::Hidden);
48 STATISTIC(numIntervals, "Number of original intervals");
49 STATISTIC(numIntervalsAfter, "Number of intervals after coalescing");
50 STATISTIC(numFolds , "Number of loads/stores folded into instructions");
51 STATISTIC(numSplits , "Number of intervals split");
53 char LiveIntervals::ID = 0;
54 static RegisterPass<LiveIntervals> X("liveintervals", "Live Interval Analysis");
56 void LiveIntervals::getAnalysisUsage(AnalysisUsage &AU) const {
57 AU.addPreserved<LiveVariables>();
58 AU.addRequired<LiveVariables>();
59 AU.addPreservedID(MachineLoopInfoID);
60 AU.addPreservedID(MachineDominatorsID);
61 AU.addPreservedID(PHIEliminationID);
62 AU.addRequiredID(PHIEliminationID);
63 AU.addRequiredID(TwoAddressInstructionPassID);
64 MachineFunctionPass::getAnalysisUsage(AU);
67 void LiveIntervals::releaseMemory() {
73 // Release VNInfo memroy regions after all VNInfo objects are dtor'd.
74 VNInfoAllocator.Reset();
75 for (unsigned i = 0, e = ClonedMIs.size(); i != e; ++i)
76 mf_->DeleteMachineInstr(ClonedMIs[i]);
79 void LiveIntervals::computeNumbering() {
80 Index2MiMap OldI2MI = i2miMap_;
87 // Number MachineInstrs and MachineBasicBlocks.
88 // Initialize MBB indexes to a sentinal.
89 MBB2IdxMap.resize(mf_->getNumBlockIDs(), std::make_pair(~0U,~0U));
92 for (MachineFunction::iterator MBB = mf_->begin(), E = mf_->end();
94 unsigned StartIdx = MIIndex;
96 for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
98 bool inserted = mi2iMap_.insert(std::make_pair(I, MIIndex)).second;
99 assert(inserted && "multiple MachineInstr -> index mappings");
100 i2miMap_.push_back(I);
101 MIIndex += InstrSlots::NUM;
104 if (StartIdx == MIIndex) {
106 MIIndex += InstrSlots::NUM;
107 i2miMap_.push_back(0);
109 // Set the MBB2IdxMap entry for this MBB.
110 MBB2IdxMap[MBB->getNumber()] = std::make_pair(StartIdx, MIIndex - 1);
111 Idx2MBBMap.push_back(std::make_pair(StartIdx, MBB));
113 std::sort(Idx2MBBMap.begin(), Idx2MBBMap.end(), Idx2MBBCompare());
115 if (!OldI2MI.empty())
116 for (iterator I = begin(), E = end(); I != E; ++I)
117 for (LiveInterval::iterator LI = I->second.begin(), LE = I->second.end();
120 // Remap the start index of the live range to the corresponding new
121 // number, or our best guess at what it _should_ correspond to if the
122 // original instruction has been erased. This is either the following
123 // instruction or its predecessor.
124 unsigned offset = LI->start % InstrSlots::NUM;
125 if (OldI2MI[LI->start / InstrSlots::NUM])
126 LI->start = mi2iMap_[OldI2MI[LI->start / InstrSlots::NUM]] + offset;
129 MachineInstr* newInstr = 0;
131 newInstr = OldI2MI[LI->start / InstrSlots::NUM + i];
135 if (mi2iMap_[newInstr] ==
136 MBB2IdxMap[newInstr->getParent()->getNumber()].first)
137 LI->start = mi2iMap_[newInstr];
139 LI->start = mi2iMap_[newInstr] - InstrSlots::NUM + offset;
142 // Remap the ending index in the same way that we remapped the start,
143 // except for the final step where we always map to the immediately
144 // following instruction.
145 if (LI->end / InstrSlots::NUM < OldI2MI.size()) {
146 offset = LI->end % InstrSlots::NUM;
147 if (OldI2MI[LI->end / InstrSlots::NUM])
148 LI->end = mi2iMap_[OldI2MI[LI->end / InstrSlots::NUM]] + offset;
151 MachineInstr* newInstr = 0;
153 newInstr = OldI2MI[LI->end / InstrSlots::NUM + i];
157 LI->end = mi2iMap_[newInstr];
160 LI->end = i2miMap_.size() * InstrSlots::NUM;
163 // Remap the VNInfo def index, which works the same as the
164 // start indices above.
165 VNInfo* vni = LI->valno;
166 offset = vni->def % InstrSlots::NUM;
167 if (OldI2MI[vni->def / InstrSlots::NUM])
168 vni->def = mi2iMap_[OldI2MI[vni->def / InstrSlots::NUM]] + offset;
171 MachineInstr* newInstr = 0;
173 newInstr = OldI2MI[vni->def / InstrSlots::NUM + i];
177 if (mi2iMap_[newInstr] ==
178 MBB2IdxMap[newInstr->getParent()->getNumber()].first)
179 vni->def = mi2iMap_[newInstr];
181 vni->def = mi2iMap_[newInstr] - InstrSlots::NUM + offset;
184 // Remap the VNInfo kill indices, which works the same as
185 // the end indices above.
186 for (size_t i = 0; i < vni->kills.size(); ++i) {
187 offset = vni->kills[i] % InstrSlots::NUM;
188 if (OldI2MI[vni->kills[i] / InstrSlots::NUM])
189 vni->kills[i] = mi2iMap_[OldI2MI[vni->kills[i] / InstrSlots::NUM]] +
193 MachineInstr* newInstr = 0;
195 newInstr = OldI2MI[vni->kills[i] / InstrSlots::NUM + e];
199 vni->kills[i] = mi2iMap_[newInstr];
205 /// runOnMachineFunction - Register allocate the whole function
207 bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
209 mri_ = &mf_->getRegInfo();
210 tm_ = &fn.getTarget();
211 tri_ = tm_->getRegisterInfo();
212 tii_ = tm_->getInstrInfo();
213 lv_ = &getAnalysis<LiveVariables>();
214 allocatableRegs_ = tri_->getAllocatableSet(fn);
219 numIntervals += getNumIntervals();
221 DOUT << "********** INTERVALS **********\n";
222 for (iterator I = begin(), E = end(); I != E; ++I) {
223 I->second.print(DOUT, tri_);
227 numIntervalsAfter += getNumIntervals();
232 /// print - Implement the dump method.
233 void LiveIntervals::print(std::ostream &O, const Module* ) const {
234 O << "********** INTERVALS **********\n";
235 for (const_iterator I = begin(), E = end(); I != E; ++I) {
236 I->second.print(O, tri_);
240 O << "********** MACHINEINSTRS **********\n";
241 for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
242 mbbi != mbbe; ++mbbi) {
243 O << ((Value*)mbbi->getBasicBlock())->getName() << ":\n";
244 for (MachineBasicBlock::iterator mii = mbbi->begin(),
245 mie = mbbi->end(); mii != mie; ++mii) {
246 O << getInstructionIndex(mii) << '\t' << *mii;
251 /// conflictsWithPhysRegDef - Returns true if the specified register
252 /// is defined during the duration of the specified interval.
253 bool LiveIntervals::conflictsWithPhysRegDef(const LiveInterval &li,
254 VirtRegMap &vrm, unsigned reg) {
255 for (LiveInterval::Ranges::const_iterator
256 I = li.ranges.begin(), E = li.ranges.end(); I != E; ++I) {
257 for (unsigned index = getBaseIndex(I->start),
258 end = getBaseIndex(I->end-1) + InstrSlots::NUM; index != end;
259 index += InstrSlots::NUM) {
260 // skip deleted instructions
261 while (index != end && !getInstructionFromIndex(index))
262 index += InstrSlots::NUM;
263 if (index == end) break;
265 MachineInstr *MI = getInstructionFromIndex(index);
266 unsigned SrcReg, DstReg;
267 if (tii_->isMoveInstr(*MI, SrcReg, DstReg))
268 if (SrcReg == li.reg || DstReg == li.reg)
270 for (unsigned i = 0; i != MI->getNumOperands(); ++i) {
271 MachineOperand& mop = MI->getOperand(i);
272 if (!mop.isRegister())
274 unsigned PhysReg = mop.getReg();
275 if (PhysReg == 0 || PhysReg == li.reg)
277 if (TargetRegisterInfo::isVirtualRegister(PhysReg)) {
278 if (!vrm.hasPhys(PhysReg))
280 PhysReg = vrm.getPhys(PhysReg);
282 if (PhysReg && tri_->regsOverlap(PhysReg, reg))
291 void LiveIntervals::printRegName(unsigned reg) const {
292 if (TargetRegisterInfo::isPhysicalRegister(reg))
293 cerr << tri_->getName(reg);
295 cerr << "%reg" << reg;
298 void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock *mbb,
299 MachineBasicBlock::iterator mi,
300 unsigned MIIdx, MachineOperand& MO,
301 LiveInterval &interval) {
302 DOUT << "\t\tregister: "; DEBUG(printRegName(interval.reg));
303 LiveVariables::VarInfo& vi = lv_->getVarInfo(interval.reg);
305 if (mi->getOpcode() == TargetInstrInfo::IMPLICIT_DEF) {
306 DOUT << "is a implicit_def\n";
310 // Virtual registers may be defined multiple times (due to phi
311 // elimination and 2-addr elimination). Much of what we do only has to be
312 // done once for the vreg. We use an empty interval to detect the first
313 // time we see a vreg.
314 if (interval.empty()) {
315 // Get the Idx of the defining instructions.
316 unsigned defIndex = getDefIndex(MIIdx);
318 MachineInstr *CopyMI = NULL;
319 unsigned SrcReg, DstReg;
320 if (mi->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG ||
321 mi->getOpcode() == TargetInstrInfo::INSERT_SUBREG ||
322 tii_->isMoveInstr(*mi, SrcReg, DstReg))
324 ValNo = interval.getNextValue(defIndex, CopyMI, VNInfoAllocator);
326 assert(ValNo->id == 0 && "First value in interval is not 0?");
328 // Loop over all of the blocks that the vreg is defined in. There are
329 // two cases we have to handle here. The most common case is a vreg
330 // whose lifetime is contained within a basic block. In this case there
331 // will be a single kill, in MBB, which comes after the definition.
332 if (vi.Kills.size() == 1 && vi.Kills[0]->getParent() == mbb) {
333 // FIXME: what about dead vars?
335 if (vi.Kills[0] != mi)
336 killIdx = getUseIndex(getInstructionIndex(vi.Kills[0]))+1;
338 killIdx = defIndex+1;
340 // If the kill happens after the definition, we have an intra-block
342 if (killIdx > defIndex) {
343 assert(vi.AliveBlocks.none() &&
344 "Shouldn't be alive across any blocks!");
345 LiveRange LR(defIndex, killIdx, ValNo);
346 interval.addRange(LR);
347 DOUT << " +" << LR << "\n";
348 interval.addKill(ValNo, killIdx);
353 // The other case we handle is when a virtual register lives to the end
354 // of the defining block, potentially live across some blocks, then is
355 // live into some number of blocks, but gets killed. Start by adding a
356 // range that goes from this definition to the end of the defining block.
357 LiveRange NewLR(defIndex,
358 getInstructionIndex(&mbb->back()) + InstrSlots::NUM,
360 DOUT << " +" << NewLR;
361 interval.addRange(NewLR);
363 // Iterate over all of the blocks that the variable is completely
364 // live in, adding [insrtIndex(begin), instrIndex(end)+4) to the
366 for (unsigned i = 0, e = vi.AliveBlocks.size(); i != e; ++i) {
367 if (vi.AliveBlocks[i]) {
368 LiveRange LR(getMBBStartIdx(i),
369 getMBBEndIdx(i)+1, // MBB ends at -1.
371 interval.addRange(LR);
376 // Finally, this virtual register is live from the start of any killing
377 // block to the 'use' slot of the killing instruction.
378 for (unsigned i = 0, e = vi.Kills.size(); i != e; ++i) {
379 MachineInstr *Kill = vi.Kills[i];
380 unsigned killIdx = getUseIndex(getInstructionIndex(Kill))+1;
381 LiveRange LR(getMBBStartIdx(Kill->getParent()),
383 interval.addRange(LR);
384 interval.addKill(ValNo, killIdx);
389 // If this is the second time we see a virtual register definition, it
390 // must be due to phi elimination or two addr elimination. If this is
391 // the result of two address elimination, then the vreg is one of the
392 // def-and-use register operand.
393 if (mi->isRegReDefinedByTwoAddr(interval.reg)) {
394 // If this is a two-address definition, then we have already processed
395 // the live range. The only problem is that we didn't realize there
396 // are actually two values in the live interval. Because of this we
397 // need to take the LiveRegion that defines this register and split it
399 assert(interval.containsOneValue());
400 unsigned DefIndex = getDefIndex(interval.getValNumInfo(0)->def);
401 unsigned RedefIndex = getDefIndex(MIIdx);
403 const LiveRange *OldLR = interval.getLiveRangeContaining(RedefIndex-1);
404 VNInfo *OldValNo = OldLR->valno;
406 // Delete the initial value, which should be short and continuous,
407 // because the 2-addr copy must be in the same MBB as the redef.
408 interval.removeRange(DefIndex, RedefIndex);
410 // Two-address vregs should always only be redefined once. This means
411 // that at this point, there should be exactly one value number in it.
412 assert(interval.containsOneValue() && "Unexpected 2-addr liveint!");
414 // The new value number (#1) is defined by the instruction we claimed
416 VNInfo *ValNo = interval.getNextValue(OldValNo->def, OldValNo->copy,
419 // Value#0 is now defined by the 2-addr instruction.
420 OldValNo->def = RedefIndex;
423 // Add the new live interval which replaces the range for the input copy.
424 LiveRange LR(DefIndex, RedefIndex, ValNo);
425 DOUT << " replace range with " << LR;
426 interval.addRange(LR);
427 interval.addKill(ValNo, RedefIndex);
429 // If this redefinition is dead, we need to add a dummy unit live
430 // range covering the def slot.
432 interval.addRange(LiveRange(RedefIndex, RedefIndex+1, OldValNo));
435 interval.print(DOUT, tri_);
438 // Otherwise, this must be because of phi elimination. If this is the
439 // first redefinition of the vreg that we have seen, go back and change
440 // the live range in the PHI block to be a different value number.
441 if (interval.containsOneValue()) {
442 assert(vi.Kills.size() == 1 &&
443 "PHI elimination vreg should have one kill, the PHI itself!");
445 // Remove the old range that we now know has an incorrect number.
446 VNInfo *VNI = interval.getValNumInfo(0);
447 MachineInstr *Killer = vi.Kills[0];
448 unsigned Start = getMBBStartIdx(Killer->getParent());
449 unsigned End = getUseIndex(getInstructionIndex(Killer))+1;
450 DOUT << " Removing [" << Start << "," << End << "] from: ";
451 interval.print(DOUT, tri_); DOUT << "\n";
452 interval.removeRange(Start, End);
453 VNI->hasPHIKill = true;
454 DOUT << " RESULT: "; interval.print(DOUT, tri_);
456 // Replace the interval with one of a NEW value number. Note that this
457 // value number isn't actually defined by an instruction, weird huh? :)
458 LiveRange LR(Start, End, interval.getNextValue(~0, 0, VNInfoAllocator));
459 DOUT << " replace range with " << LR;
460 interval.addRange(LR);
461 interval.addKill(LR.valno, End);
462 DOUT << " RESULT: "; interval.print(DOUT, tri_);
465 // In the case of PHI elimination, each variable definition is only
466 // live until the end of the block. We've already taken care of the
467 // rest of the live range.
468 unsigned defIndex = getDefIndex(MIIdx);
471 MachineInstr *CopyMI = NULL;
472 unsigned SrcReg, DstReg;
473 if (mi->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG ||
474 mi->getOpcode() == TargetInstrInfo::INSERT_SUBREG ||
475 tii_->isMoveInstr(*mi, SrcReg, DstReg))
477 ValNo = interval.getNextValue(defIndex, CopyMI, VNInfoAllocator);
479 unsigned killIndex = getInstructionIndex(&mbb->back()) + InstrSlots::NUM;
480 LiveRange LR(defIndex, killIndex, ValNo);
481 interval.addRange(LR);
482 interval.addKill(ValNo, killIndex);
483 ValNo->hasPHIKill = true;
491 void LiveIntervals::handlePhysicalRegisterDef(MachineBasicBlock *MBB,
492 MachineBasicBlock::iterator mi,
495 LiveInterval &interval,
496 MachineInstr *CopyMI) {
497 // A physical register cannot be live across basic block, so its
498 // lifetime must end somewhere in its defining basic block.
499 DOUT << "\t\tregister: "; DEBUG(printRegName(interval.reg));
501 unsigned baseIndex = MIIdx;
502 unsigned start = getDefIndex(baseIndex);
503 unsigned end = start;
505 // If it is not used after definition, it is considered dead at
506 // the instruction defining it. Hence its interval is:
507 // [defSlot(def), defSlot(def)+1)
510 end = getDefIndex(start) + 1;
514 // If it is not dead on definition, it must be killed by a
515 // subsequent instruction. Hence its interval is:
516 // [defSlot(def), useSlot(kill)+1)
517 while (++mi != MBB->end()) {
518 baseIndex += InstrSlots::NUM;
519 if (mi->killsRegister(interval.reg, tri_)) {
521 end = getUseIndex(baseIndex) + 1;
523 } else if (mi->modifiesRegister(interval.reg, tri_)) {
524 // Another instruction redefines the register before it is ever read.
525 // Then the register is essentially dead at the instruction that defines
526 // it. Hence its interval is:
527 // [defSlot(def), defSlot(def)+1)
529 end = getDefIndex(start) + 1;
534 // The only case we should have a dead physreg here without a killing or
535 // instruction where we know it's dead is if it is live-in to the function
537 assert(!CopyMI && "physreg was not killed in defining block!");
538 end = getDefIndex(start) + 1; // It's dead.
541 assert(start < end && "did not find end of interval?");
543 // Already exists? Extend old live interval.
544 LiveInterval::iterator OldLR = interval.FindLiveRangeContaining(start);
545 VNInfo *ValNo = (OldLR != interval.end())
546 ? OldLR->valno : interval.getNextValue(start, CopyMI, VNInfoAllocator);
547 LiveRange LR(start, end, ValNo);
548 interval.addRange(LR);
549 interval.addKill(LR.valno, end);
550 DOUT << " +" << LR << '\n';
553 void LiveIntervals::handleRegisterDef(MachineBasicBlock *MBB,
554 MachineBasicBlock::iterator MI,
556 MachineOperand& MO) {
557 if (TargetRegisterInfo::isVirtualRegister(MO.getReg()))
558 handleVirtualRegisterDef(MBB, MI, MIIdx, MO,
559 getOrCreateInterval(MO.getReg()));
560 else if (allocatableRegs_[MO.getReg()]) {
561 MachineInstr *CopyMI = NULL;
562 unsigned SrcReg, DstReg;
563 if (MI->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG ||
564 MI->getOpcode() == TargetInstrInfo::INSERT_SUBREG ||
565 tii_->isMoveInstr(*MI, SrcReg, DstReg))
567 handlePhysicalRegisterDef(MBB, MI, MIIdx, MO,
568 getOrCreateInterval(MO.getReg()), CopyMI);
569 // Def of a register also defines its sub-registers.
570 for (const unsigned* AS = tri_->getSubRegisters(MO.getReg()); *AS; ++AS)
571 // If MI also modifies the sub-register explicitly, avoid processing it
572 // more than once. Do not pass in TRI here so it checks for exact match.
573 if (!MI->modifiesRegister(*AS))
574 handlePhysicalRegisterDef(MBB, MI, MIIdx, MO,
575 getOrCreateInterval(*AS), 0);
579 void LiveIntervals::handleLiveInRegister(MachineBasicBlock *MBB,
581 LiveInterval &interval, bool isAlias) {
582 DOUT << "\t\tlivein register: "; DEBUG(printRegName(interval.reg));
584 // Look for kills, if it reaches a def before it's killed, then it shouldn't
585 // be considered a livein.
586 MachineBasicBlock::iterator mi = MBB->begin();
587 unsigned baseIndex = MIIdx;
588 unsigned start = baseIndex;
589 unsigned end = start;
590 while (mi != MBB->end()) {
591 if (mi->killsRegister(interval.reg, tri_)) {
593 end = getUseIndex(baseIndex) + 1;
595 } else if (mi->modifiesRegister(interval.reg, tri_)) {
596 // Another instruction redefines the register before it is ever read.
597 // Then the register is essentially dead at the instruction that defines
598 // it. Hence its interval is:
599 // [defSlot(def), defSlot(def)+1)
601 end = getDefIndex(start) + 1;
605 baseIndex += InstrSlots::NUM;
610 // Live-in register might not be used at all.
614 end = getDefIndex(MIIdx) + 1;
616 DOUT << " live through";
621 LiveRange LR(start, end, interval.getNextValue(start, 0, VNInfoAllocator));
622 interval.addRange(LR);
623 interval.addKill(LR.valno, end);
624 DOUT << " +" << LR << '\n';
627 /// computeIntervals - computes the live intervals for virtual
628 /// registers. for some ordering of the machine instructions [1,N] a
629 /// live interval is an interval [i, j) where 1 <= i <= j < N for
630 /// which a variable is live
631 void LiveIntervals::computeIntervals() {
632 DOUT << "********** COMPUTING LIVE INTERVALS **********\n"
633 << "********** Function: "
634 << ((Value*)mf_->getFunction())->getName() << '\n';
635 // Track the index of the current machine instr.
636 unsigned MIIndex = 0;
637 for (MachineFunction::iterator MBBI = mf_->begin(), E = mf_->end();
639 MachineBasicBlock *MBB = MBBI;
640 DOUT << ((Value*)MBB->getBasicBlock())->getName() << ":\n";
642 MachineBasicBlock::iterator MI = MBB->begin(), miEnd = MBB->end();
644 // Create intervals for live-ins to this BB first.
645 for (MachineBasicBlock::const_livein_iterator LI = MBB->livein_begin(),
646 LE = MBB->livein_end(); LI != LE; ++LI) {
647 handleLiveInRegister(MBB, MIIndex, getOrCreateInterval(*LI));
648 // Multiple live-ins can alias the same register.
649 for (const unsigned* AS = tri_->getSubRegisters(*LI); *AS; ++AS)
650 if (!hasInterval(*AS))
651 handleLiveInRegister(MBB, MIIndex, getOrCreateInterval(*AS),
655 for (; MI != miEnd; ++MI) {
656 DOUT << MIIndex << "\t" << *MI;
659 for (int i = MI->getNumOperands() - 1; i >= 0; --i) {
660 MachineOperand &MO = MI->getOperand(i);
661 // handle register defs - build intervals
662 if (MO.isRegister() && MO.getReg() && MO.isDef())
663 handleRegisterDef(MBB, MI, MIIndex, MO);
666 MIIndex += InstrSlots::NUM;
669 if (MBB->begin() == miEnd) MIIndex += InstrSlots::NUM; // Empty MBB
673 bool LiveIntervals::findLiveInMBBs(const LiveRange &LR,
674 SmallVectorImpl<MachineBasicBlock*> &MBBs) const {
675 std::vector<IdxMBBPair>::const_iterator I =
676 std::lower_bound(Idx2MBBMap.begin(), Idx2MBBMap.end(), LR.start);
679 while (I != Idx2MBBMap.end()) {
680 if (LR.end <= I->first)
682 MBBs.push_back(I->second);
690 LiveInterval LiveIntervals::createInterval(unsigned reg) {
691 float Weight = TargetRegisterInfo::isPhysicalRegister(reg) ?
693 return LiveInterval(reg, Weight);
696 /// getVNInfoSourceReg - Helper function that parses the specified VNInfo
697 /// copy field and returns the source register that defines it.
698 unsigned LiveIntervals::getVNInfoSourceReg(const VNInfo *VNI) const {
702 if (VNI->copy->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG)
703 return VNI->copy->getOperand(1).getReg();
704 if (VNI->copy->getOpcode() == TargetInstrInfo::INSERT_SUBREG)
705 return VNI->copy->getOperand(2).getReg();
706 unsigned SrcReg, DstReg;
707 if (tii_->isMoveInstr(*VNI->copy, SrcReg, DstReg))
709 assert(0 && "Unrecognized copy instruction!");
713 //===----------------------------------------------------------------------===//
714 // Register allocator hooks.
717 /// getReMatImplicitUse - If the remat definition MI has one (for now, we only
718 /// allow one) virtual register operand, then its uses are implicitly using
719 /// the register. Returns the virtual register.
720 unsigned LiveIntervals::getReMatImplicitUse(const LiveInterval &li,
721 MachineInstr *MI) const {
723 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
724 MachineOperand &MO = MI->getOperand(i);
725 if (!MO.isRegister() || !MO.isUse())
727 unsigned Reg = MO.getReg();
728 if (Reg == 0 || Reg == li.reg)
730 // FIXME: For now, only remat MI with at most one register operand.
732 "Can't rematerialize instruction with multiple register operand!");
739 /// isValNoAvailableAt - Return true if the val# of the specified interval
740 /// which reaches the given instruction also reaches the specified use index.
741 bool LiveIntervals::isValNoAvailableAt(const LiveInterval &li, MachineInstr *MI,
742 unsigned UseIdx) const {
743 unsigned Index = getInstructionIndex(MI);
744 VNInfo *ValNo = li.FindLiveRangeContaining(Index)->valno;
745 LiveInterval::const_iterator UI = li.FindLiveRangeContaining(UseIdx);
746 return UI != li.end() && UI->valno == ValNo;
749 /// isReMaterializable - Returns true if the definition MI of the specified
750 /// val# of the specified interval is re-materializable.
751 bool LiveIntervals::isReMaterializable(const LiveInterval &li,
752 const VNInfo *ValNo, MachineInstr *MI,
758 if (MI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF)
762 if (tii_->isLoadFromStackSlot(MI, FrameIdx) &&
763 mf_->getFrameInfo()->isImmutableObjectIndex(FrameIdx))
764 // FIXME: Let target specific isReallyTriviallyReMaterializable determines
765 // this but remember this is not safe to fold into a two-address
767 // This is a load from fixed stack slot. It can be rematerialized.
770 if (tii_->isTriviallyReMaterializable(MI)) {
771 const TargetInstrDesc &TID = MI->getDesc();
772 isLoad = TID.isSimpleLoad();
774 unsigned ImpUse = getReMatImplicitUse(li, MI);
776 const LiveInterval &ImpLi = getInterval(ImpUse);
777 for (MachineRegisterInfo::use_iterator ri = mri_->use_begin(li.reg),
778 re = mri_->use_end(); ri != re; ++ri) {
779 MachineInstr *UseMI = &*ri;
780 unsigned UseIdx = getInstructionIndex(UseMI);
781 if (li.FindLiveRangeContaining(UseIdx)->valno != ValNo)
783 if (!isValNoAvailableAt(ImpLi, MI, UseIdx))
793 /// isReMaterializable - Returns true if every definition of MI of every
794 /// val# of the specified interval is re-materializable.
795 bool LiveIntervals::isReMaterializable(const LiveInterval &li, bool &isLoad) {
797 for (LiveInterval::const_vni_iterator i = li.vni_begin(), e = li.vni_end();
799 const VNInfo *VNI = *i;
800 unsigned DefIdx = VNI->def;
802 continue; // Dead val#.
803 // Is the def for the val# rematerializable?
806 MachineInstr *ReMatDefMI = getInstructionFromIndex(DefIdx);
807 bool DefIsLoad = false;
809 !isReMaterializable(li, VNI, ReMatDefMI, DefIsLoad))
816 /// FilterFoldedOps - Filter out two-address use operands. Return
817 /// true if it finds any issue with the operands that ought to prevent
819 static bool FilterFoldedOps(MachineInstr *MI,
820 SmallVector<unsigned, 2> &Ops,
822 SmallVector<unsigned, 2> &FoldOps) {
823 const TargetInstrDesc &TID = MI->getDesc();
826 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
827 unsigned OpIdx = Ops[i];
828 MachineOperand &MO = MI->getOperand(OpIdx);
829 // FIXME: fold subreg use.
833 MRInfo |= (unsigned)VirtRegMap::isMod;
835 // Filter out two-address use operand(s).
836 if (!MO.isImplicit() &&
837 TID.getOperandConstraint(OpIdx, TOI::TIED_TO) != -1) {
838 MRInfo = VirtRegMap::isModRef;
841 MRInfo |= (unsigned)VirtRegMap::isRef;
843 FoldOps.push_back(OpIdx);
849 /// tryFoldMemoryOperand - Attempts to fold either a spill / restore from
850 /// slot / to reg or any rematerialized load into ith operand of specified
851 /// MI. If it is successul, MI is updated with the newly created MI and
853 bool LiveIntervals::tryFoldMemoryOperand(MachineInstr* &MI,
854 VirtRegMap &vrm, MachineInstr *DefMI,
856 SmallVector<unsigned, 2> &Ops,
857 bool isSS, int Slot, unsigned Reg) {
858 // If it is an implicit def instruction, just delete it.
859 if (MI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF) {
860 RemoveMachineInstrFromMaps(MI);
861 vrm.RemoveMachineInstrFromMaps(MI);
862 MI->eraseFromParent();
867 // Filter the list of operand indexes that are to be folded. Abort if
868 // any operand will prevent folding.
870 SmallVector<unsigned, 2> FoldOps;
871 if (FilterFoldedOps(MI, Ops, MRInfo, FoldOps))
874 // The only time it's safe to fold into a two address instruction is when
875 // it's folding reload and spill from / into a spill stack slot.
876 if (DefMI && (MRInfo & VirtRegMap::isMod))
879 MachineInstr *fmi = isSS ? tii_->foldMemoryOperand(*mf_, MI, FoldOps, Slot)
880 : tii_->foldMemoryOperand(*mf_, MI, FoldOps, DefMI);
882 // Remember this instruction uses the spill slot.
883 if (isSS) vrm.addSpillSlotUse(Slot, fmi);
885 // Attempt to fold the memory reference into the instruction. If
886 // we can do this, we don't need to insert spill code.
887 MachineBasicBlock &MBB = *MI->getParent();
888 if (isSS && !mf_->getFrameInfo()->isImmutableObjectIndex(Slot))
889 vrm.virtFolded(Reg, MI, fmi, (VirtRegMap::ModRef)MRInfo);
890 vrm.transferSpillPts(MI, fmi);
891 vrm.transferRestorePts(MI, fmi);
892 vrm.transferEmergencySpills(MI, fmi);
894 i2miMap_[InstrIdx /InstrSlots::NUM] = fmi;
895 mi2iMap_[fmi] = InstrIdx;
896 MI = MBB.insert(MBB.erase(MI), fmi);
903 /// canFoldMemoryOperand - Returns true if the specified load / store
904 /// folding is possible.
905 bool LiveIntervals::canFoldMemoryOperand(MachineInstr *MI,
906 SmallVector<unsigned, 2> &Ops,
908 // Filter the list of operand indexes that are to be folded. Abort if
909 // any operand will prevent folding.
911 SmallVector<unsigned, 2> FoldOps;
912 if (FilterFoldedOps(MI, Ops, MRInfo, FoldOps))
915 // It's only legal to remat for a use, not a def.
916 if (ReMat && (MRInfo & VirtRegMap::isMod))
919 return tii_->canFoldMemoryOperand(MI, FoldOps);
922 bool LiveIntervals::intervalIsInOneMBB(const LiveInterval &li) const {
923 SmallPtrSet<MachineBasicBlock*, 4> MBBs;
924 for (LiveInterval::Ranges::const_iterator
925 I = li.ranges.begin(), E = li.ranges.end(); I != E; ++I) {
926 std::vector<IdxMBBPair>::const_iterator II =
927 std::lower_bound(Idx2MBBMap.begin(), Idx2MBBMap.end(), I->start);
928 if (II == Idx2MBBMap.end())
930 if (I->end > II->first) // crossing a MBB.
932 MBBs.insert(II->second);
939 /// rewriteImplicitOps - Rewrite implicit use operands of MI (i.e. uses of
940 /// interval on to-be re-materialized operands of MI) with new register.
941 void LiveIntervals::rewriteImplicitOps(const LiveInterval &li,
942 MachineInstr *MI, unsigned NewVReg,
944 // There is an implicit use. That means one of the other operand is
945 // being remat'ed and the remat'ed instruction has li.reg as an
946 // use operand. Make sure we rewrite that as well.
947 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
948 MachineOperand &MO = MI->getOperand(i);
949 if (!MO.isRegister())
951 unsigned Reg = MO.getReg();
952 if (Reg == 0 || TargetRegisterInfo::isPhysicalRegister(Reg))
954 if (!vrm.isReMaterialized(Reg))
956 MachineInstr *ReMatMI = vrm.getReMaterializedMI(Reg);
957 MachineOperand *UseMO = ReMatMI->findRegisterUseOperand(li.reg);
959 UseMO->setReg(NewVReg);
963 /// rewriteInstructionForSpills, rewriteInstructionsForSpills - Helper functions
964 /// for addIntervalsForSpills to rewrite uses / defs for the given live range.
966 rewriteInstructionForSpills(const LiveInterval &li, const VNInfo *VNI,
967 bool TrySplit, unsigned index, unsigned end, MachineInstr *MI,
968 MachineInstr *ReMatOrigDefMI, MachineInstr *ReMatDefMI,
969 unsigned Slot, int LdSlot,
970 bool isLoad, bool isLoadSS, bool DefIsReMat, bool CanDelete,
972 const TargetRegisterClass* rc,
973 SmallVector<int, 4> &ReMatIds,
974 const MachineLoopInfo *loopInfo,
975 unsigned &NewVReg, unsigned ImpUse, bool &HasDef, bool &HasUse,
976 std::map<unsigned,unsigned> &MBBVRegsMap,
977 std::vector<LiveInterval*> &NewLIs, float &SSWeight) {
978 MachineBasicBlock *MBB = MI->getParent();
979 unsigned loopDepth = loopInfo->getLoopDepth(MBB);
980 bool CanFold = false;
982 for (unsigned i = 0; i != MI->getNumOperands(); ++i) {
983 MachineOperand& mop = MI->getOperand(i);
984 if (!mop.isRegister())
986 unsigned Reg = mop.getReg();
988 if (Reg == 0 || TargetRegisterInfo::isPhysicalRegister(Reg))
993 bool TryFold = !DefIsReMat;
994 bool FoldSS = true; // Default behavior unless it's a remat.
997 // If this is the rematerializable definition MI itself and
998 // all of its uses are rematerialized, simply delete it.
999 if (MI == ReMatOrigDefMI && CanDelete) {
1000 DOUT << "\t\t\t\tErasing re-materlizable def: ";
1002 RemoveMachineInstrFromMaps(MI);
1003 vrm.RemoveMachineInstrFromMaps(MI);
1004 MI->eraseFromParent();
1008 // If def for this use can't be rematerialized, then try folding.
1009 // If def is rematerializable and it's a load, also try folding.
1010 TryFold = !ReMatDefMI || (ReMatDefMI && (MI == ReMatOrigDefMI || isLoad));
1012 // Try fold loads (from stack slot, constant pool, etc.) into uses.
1018 // Scan all of the operands of this instruction rewriting operands
1019 // to use NewVReg instead of li.reg as appropriate. We do this for
1022 // 1. If the instr reads the same spilled vreg multiple times, we
1023 // want to reuse the NewVReg.
1024 // 2. If the instr is a two-addr instruction, we are required to
1025 // keep the src/dst regs pinned.
1027 // Keep track of whether we replace a use and/or def so that we can
1028 // create the spill interval with the appropriate range.
1030 HasUse = mop.isUse();
1031 HasDef = mop.isDef();
1032 SmallVector<unsigned, 2> Ops;
1034 for (unsigned j = i+1, e = MI->getNumOperands(); j != e; ++j) {
1035 const MachineOperand &MOj = MI->getOperand(j);
1036 if (!MOj.isRegister())
1038 unsigned RegJ = MOj.getReg();
1039 if (RegJ == 0 || TargetRegisterInfo::isPhysicalRegister(RegJ))
1043 HasUse |= MOj.isUse();
1044 HasDef |= MOj.isDef();
1048 // Update stack slot spill weight if we are splitting.
1049 float Weight = getSpillWeight(HasDef, HasUse, loopDepth);
1056 // Do not fold load / store here if we are splitting. We'll find an
1057 // optimal point to insert a load / store later.
1059 if (tryFoldMemoryOperand(MI, vrm, ReMatDefMI, index,
1060 Ops, FoldSS, FoldSlot, Reg)) {
1061 // Folding the load/store can completely change the instruction in
1062 // unpredictable ways, rescan it from the beginning.
1066 if (isRemoved(MI)) {
1070 goto RestartInstruction;
1073 // We'll try to fold it later if it's profitable.
1074 CanFold = canFoldMemoryOperand(MI, Ops, DefIsReMat);
1078 // Create a new virtual register for the spill interval.
1079 bool CreatedNewVReg = false;
1081 NewVReg = mri_->createVirtualRegister(rc);
1083 CreatedNewVReg = true;
1085 mop.setReg(NewVReg);
1086 if (mop.isImplicit())
1087 rewriteImplicitOps(li, MI, NewVReg, vrm);
1089 // Reuse NewVReg for other reads.
1090 for (unsigned j = 0, e = Ops.size(); j != e; ++j) {
1091 MachineOperand &mopj = MI->getOperand(Ops[j]);
1092 mopj.setReg(NewVReg);
1093 if (mopj.isImplicit())
1094 rewriteImplicitOps(li, MI, NewVReg, vrm);
1097 if (CreatedNewVReg) {
1099 vrm.setVirtIsReMaterialized(NewVReg, ReMatDefMI/*, CanDelete*/);
1100 if (ReMatIds[VNI->id] == VirtRegMap::MAX_STACK_SLOT) {
1101 // Each valnum may have its own remat id.
1102 ReMatIds[VNI->id] = vrm.assignVirtReMatId(NewVReg);
1104 vrm.assignVirtReMatId(NewVReg, ReMatIds[VNI->id]);
1106 if (!CanDelete || (HasUse && HasDef)) {
1107 // If this is a two-addr instruction then its use operands are
1108 // rematerializable but its def is not. It should be assigned a
1110 vrm.assignVirt2StackSlot(NewVReg, Slot);
1113 vrm.assignVirt2StackSlot(NewVReg, Slot);
1115 } else if (HasUse && HasDef &&
1116 vrm.getStackSlot(NewVReg) == VirtRegMap::NO_STACK_SLOT) {
1117 // If this interval hasn't been assigned a stack slot (because earlier
1118 // def is a deleted remat def), do it now.
1119 assert(Slot != VirtRegMap::NO_STACK_SLOT);
1120 vrm.assignVirt2StackSlot(NewVReg, Slot);
1123 // Re-matting an instruction with virtual register use. Add the
1124 // register as an implicit use on the use MI.
1125 if (DefIsReMat && ImpUse)
1126 MI->addOperand(MachineOperand::CreateReg(ImpUse, false, true));
1128 // create a new register interval for this spill / remat.
1129 LiveInterval &nI = getOrCreateInterval(NewVReg);
1130 if (CreatedNewVReg) {
1131 NewLIs.push_back(&nI);
1132 MBBVRegsMap.insert(std::make_pair(MI->getParent()->getNumber(), NewVReg));
1134 vrm.setIsSplitFromReg(NewVReg, li.reg);
1138 if (CreatedNewVReg) {
1139 LiveRange LR(getLoadIndex(index), getUseIndex(index)+1,
1140 nI.getNextValue(~0U, 0, VNInfoAllocator));
1144 // Extend the split live interval to this def / use.
1145 unsigned End = getUseIndex(index)+1;
1146 LiveRange LR(nI.ranges[nI.ranges.size()-1].end, End,
1147 nI.getValNumInfo(nI.getNumValNums()-1));
1153 LiveRange LR(getDefIndex(index), getStoreIndex(index),
1154 nI.getNextValue(~0U, 0, VNInfoAllocator));
1159 DOUT << "\t\t\t\tAdded new interval: ";
1160 nI.print(DOUT, tri_);
1165 bool LiveIntervals::anyKillInMBBAfterIdx(const LiveInterval &li,
1167 MachineBasicBlock *MBB, unsigned Idx) const {
1168 unsigned End = getMBBEndIdx(MBB);
1169 for (unsigned j = 0, ee = VNI->kills.size(); j != ee; ++j) {
1170 unsigned KillIdx = VNI->kills[j];
1171 if (KillIdx > Idx && KillIdx < End)
1177 /// RewriteInfo - Keep track of machine instrs that will be rewritten
1178 /// during spilling.
1180 struct RewriteInfo {
1185 RewriteInfo(unsigned i, MachineInstr *mi, bool u, bool d)
1186 : Index(i), MI(mi), HasUse(u), HasDef(d) {}
1189 struct RewriteInfoCompare {
1190 bool operator()(const RewriteInfo &LHS, const RewriteInfo &RHS) const {
1191 return LHS.Index < RHS.Index;
1196 void LiveIntervals::
1197 rewriteInstructionsForSpills(const LiveInterval &li, bool TrySplit,
1198 LiveInterval::Ranges::const_iterator &I,
1199 MachineInstr *ReMatOrigDefMI, MachineInstr *ReMatDefMI,
1200 unsigned Slot, int LdSlot,
1201 bool isLoad, bool isLoadSS, bool DefIsReMat, bool CanDelete,
1203 const TargetRegisterClass* rc,
1204 SmallVector<int, 4> &ReMatIds,
1205 const MachineLoopInfo *loopInfo,
1206 BitVector &SpillMBBs,
1207 std::map<unsigned, std::vector<SRInfo> > &SpillIdxes,
1208 BitVector &RestoreMBBs,
1209 std::map<unsigned, std::vector<SRInfo> > &RestoreIdxes,
1210 std::map<unsigned,unsigned> &MBBVRegsMap,
1211 std::vector<LiveInterval*> &NewLIs, float &SSWeight) {
1212 bool AllCanFold = true;
1213 unsigned NewVReg = 0;
1214 unsigned start = getBaseIndex(I->start);
1215 unsigned end = getBaseIndex(I->end-1) + InstrSlots::NUM;
1217 // First collect all the def / use in this live range that will be rewritten.
1218 // Make sure they are sorted according to instruction index.
1219 std::vector<RewriteInfo> RewriteMIs;
1220 for (MachineRegisterInfo::reg_iterator ri = mri_->reg_begin(li.reg),
1221 re = mri_->reg_end(); ri != re; ) {
1222 MachineInstr *MI = &*ri;
1223 MachineOperand &O = ri.getOperand();
1225 assert(!O.isImplicit() && "Spilling register that's used as implicit use?");
1226 unsigned index = getInstructionIndex(MI);
1227 if (index < start || index >= end)
1229 RewriteMIs.push_back(RewriteInfo(index, MI, O.isUse(), O.isDef()));
1231 std::sort(RewriteMIs.begin(), RewriteMIs.end(), RewriteInfoCompare());
1233 unsigned ImpUse = DefIsReMat ? getReMatImplicitUse(li, ReMatDefMI) : 0;
1234 // Now rewrite the defs and uses.
1235 for (unsigned i = 0, e = RewriteMIs.size(); i != e; ) {
1236 RewriteInfo &rwi = RewriteMIs[i];
1238 unsigned index = rwi.Index;
1239 bool MIHasUse = rwi.HasUse;
1240 bool MIHasDef = rwi.HasDef;
1241 MachineInstr *MI = rwi.MI;
1242 // If MI def and/or use the same register multiple times, then there
1243 // are multiple entries.
1244 unsigned NumUses = MIHasUse;
1245 while (i != e && RewriteMIs[i].MI == MI) {
1246 assert(RewriteMIs[i].Index == index);
1247 bool isUse = RewriteMIs[i].HasUse;
1248 if (isUse) ++NumUses;
1250 MIHasDef |= RewriteMIs[i].HasDef;
1253 MachineBasicBlock *MBB = MI->getParent();
1255 if (ImpUse && MI != ReMatDefMI) {
1256 // Re-matting an instruction with virtual register use. Update the
1257 // register interval's spill weight to HUGE_VALF to prevent it from
1259 LiveInterval &ImpLi = getInterval(ImpUse);
1260 ImpLi.weight = HUGE_VALF;
1263 unsigned MBBId = MBB->getNumber();
1264 unsigned ThisVReg = 0;
1266 std::map<unsigned,unsigned>::const_iterator NVI = MBBVRegsMap.find(MBBId);
1267 if (NVI != MBBVRegsMap.end()) {
1268 ThisVReg = NVI->second;
1275 // It's better to start a new interval to avoid artifically
1276 // extend the new interval.
1277 if (MIHasDef && !MIHasUse) {
1278 MBBVRegsMap.erase(MBB->getNumber());
1284 bool IsNew = ThisVReg == 0;
1286 // This ends the previous live interval. If all of its def / use
1287 // can be folded, give it a low spill weight.
1288 if (NewVReg && TrySplit && AllCanFold) {
1289 LiveInterval &nI = getOrCreateInterval(NewVReg);
1296 bool HasDef = false;
1297 bool HasUse = false;
1298 bool CanFold = rewriteInstructionForSpills(li, I->valno, TrySplit,
1299 index, end, MI, ReMatOrigDefMI, ReMatDefMI,
1300 Slot, LdSlot, isLoad, isLoadSS, DefIsReMat,
1301 CanDelete, vrm, rc, ReMatIds, loopInfo, NewVReg,
1302 ImpUse, HasDef, HasUse, MBBVRegsMap, NewLIs, SSWeight);
1303 if (!HasDef && !HasUse)
1306 AllCanFold &= CanFold;
1308 // Update weight of spill interval.
1309 LiveInterval &nI = getOrCreateInterval(NewVReg);
1311 // The spill weight is now infinity as it cannot be spilled again.
1312 nI.weight = HUGE_VALF;
1316 // Keep track of the last def and first use in each MBB.
1318 if (MI != ReMatOrigDefMI || !CanDelete) {
1319 bool HasKill = false;
1321 HasKill = anyKillInMBBAfterIdx(li, I->valno, MBB, getDefIndex(index));
1323 // If this is a two-address code, then this index starts a new VNInfo.
1324 const VNInfo *VNI = li.findDefinedVNInfo(getDefIndex(index));
1326 HasKill = anyKillInMBBAfterIdx(li, VNI, MBB, getDefIndex(index));
1328 std::map<unsigned, std::vector<SRInfo> >::iterator SII =
1329 SpillIdxes.find(MBBId);
1331 if (SII == SpillIdxes.end()) {
1332 std::vector<SRInfo> S;
1333 S.push_back(SRInfo(index, NewVReg, true));
1334 SpillIdxes.insert(std::make_pair(MBBId, S));
1335 } else if (SII->second.back().vreg != NewVReg) {
1336 SII->second.push_back(SRInfo(index, NewVReg, true));
1337 } else if ((int)index > SII->second.back().index) {
1338 // If there is an earlier def and this is a two-address
1339 // instruction, then it's not possible to fold the store (which
1340 // would also fold the load).
1341 SRInfo &Info = SII->second.back();
1343 Info.canFold = !HasUse;
1345 SpillMBBs.set(MBBId);
1346 } else if (SII != SpillIdxes.end() &&
1347 SII->second.back().vreg == NewVReg &&
1348 (int)index > SII->second.back().index) {
1349 // There is an earlier def that's not killed (must be two-address).
1350 // The spill is no longer needed.
1351 SII->second.pop_back();
1352 if (SII->second.empty()) {
1353 SpillIdxes.erase(MBBId);
1354 SpillMBBs.reset(MBBId);
1361 std::map<unsigned, std::vector<SRInfo> >::iterator SII =
1362 SpillIdxes.find(MBBId);
1363 if (SII != SpillIdxes.end() &&
1364 SII->second.back().vreg == NewVReg &&
1365 (int)index > SII->second.back().index)
1366 // Use(s) following the last def, it's not safe to fold the spill.
1367 SII->second.back().canFold = false;
1368 std::map<unsigned, std::vector<SRInfo> >::iterator RII =
1369 RestoreIdxes.find(MBBId);
1370 if (RII != RestoreIdxes.end() && RII->second.back().vreg == NewVReg)
1371 // If we are splitting live intervals, only fold if it's the first
1372 // use and there isn't another use later in the MBB.
1373 RII->second.back().canFold = false;
1375 // Only need a reload if there isn't an earlier def / use.
1376 if (RII == RestoreIdxes.end()) {
1377 std::vector<SRInfo> Infos;
1378 Infos.push_back(SRInfo(index, NewVReg, true));
1379 RestoreIdxes.insert(std::make_pair(MBBId, Infos));
1381 RII->second.push_back(SRInfo(index, NewVReg, true));
1383 RestoreMBBs.set(MBBId);
1387 // Update spill weight.
1388 unsigned loopDepth = loopInfo->getLoopDepth(MBB);
1389 nI.weight += getSpillWeight(HasDef, HasUse, loopDepth);
1392 if (NewVReg && TrySplit && AllCanFold) {
1393 // If all of its def / use can be folded, give it a low spill weight.
1394 LiveInterval &nI = getOrCreateInterval(NewVReg);
1399 bool LiveIntervals::alsoFoldARestore(int Id, int index, unsigned vr,
1400 BitVector &RestoreMBBs,
1401 std::map<unsigned,std::vector<SRInfo> > &RestoreIdxes) {
1402 if (!RestoreMBBs[Id])
1404 std::vector<SRInfo> &Restores = RestoreIdxes[Id];
1405 for (unsigned i = 0, e = Restores.size(); i != e; ++i)
1406 if (Restores[i].index == index &&
1407 Restores[i].vreg == vr &&
1408 Restores[i].canFold)
1413 void LiveIntervals::eraseRestoreInfo(int Id, int index, unsigned vr,
1414 BitVector &RestoreMBBs,
1415 std::map<unsigned,std::vector<SRInfo> > &RestoreIdxes) {
1416 if (!RestoreMBBs[Id])
1418 std::vector<SRInfo> &Restores = RestoreIdxes[Id];
1419 for (unsigned i = 0, e = Restores.size(); i != e; ++i)
1420 if (Restores[i].index == index && Restores[i].vreg)
1421 Restores[i].index = -1;
1424 /// handleSpilledImpDefs - Remove IMPLICIT_DEF instructions which are being
1425 /// spilled and create empty intervals for their uses.
1427 LiveIntervals::handleSpilledImpDefs(const LiveInterval &li, VirtRegMap &vrm,
1428 const TargetRegisterClass* rc,
1429 std::vector<LiveInterval*> &NewLIs) {
1430 for (MachineRegisterInfo::reg_iterator ri = mri_->reg_begin(li.reg),
1431 re = mri_->reg_end(); ri != re; ) {
1432 MachineOperand &O = ri.getOperand();
1433 MachineInstr *MI = &*ri;
1436 assert(MI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF &&
1437 "Register def was not rewritten?");
1438 RemoveMachineInstrFromMaps(MI);
1439 vrm.RemoveMachineInstrFromMaps(MI);
1440 MI->eraseFromParent();
1442 // This must be an use of an implicit_def so it's not part of the live
1443 // interval. Create a new empty live interval for it.
1444 // FIXME: Can we simply erase some of the instructions? e.g. Stores?
1445 unsigned NewVReg = mri_->createVirtualRegister(rc);
1447 vrm.setIsImplicitlyDefined(NewVReg);
1448 NewLIs.push_back(&getOrCreateInterval(NewVReg));
1449 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
1450 MachineOperand &MO = MI->getOperand(i);
1451 if (MO.isReg() && MO.getReg() == li.reg)
1459 std::vector<LiveInterval*> LiveIntervals::
1460 addIntervalsForSpills(const LiveInterval &li,
1461 const MachineLoopInfo *loopInfo, VirtRegMap &vrm,
1463 assert(li.weight != HUGE_VALF &&
1464 "attempt to spill already spilled interval!");
1466 DOUT << "\t\t\t\tadding intervals for spills for interval: ";
1467 li.print(DOUT, tri_);
1470 // Spill slot weight.
1473 // Each bit specify whether it a spill is required in the MBB.
1474 BitVector SpillMBBs(mf_->getNumBlockIDs());
1475 std::map<unsigned, std::vector<SRInfo> > SpillIdxes;
1476 BitVector RestoreMBBs(mf_->getNumBlockIDs());
1477 std::map<unsigned, std::vector<SRInfo> > RestoreIdxes;
1478 std::map<unsigned,unsigned> MBBVRegsMap;
1479 std::vector<LiveInterval*> NewLIs;
1480 const TargetRegisterClass* rc = mri_->getRegClass(li.reg);
1482 unsigned NumValNums = li.getNumValNums();
1483 SmallVector<MachineInstr*, 4> ReMatDefs;
1484 ReMatDefs.resize(NumValNums, NULL);
1485 SmallVector<MachineInstr*, 4> ReMatOrigDefs;
1486 ReMatOrigDefs.resize(NumValNums, NULL);
1487 SmallVector<int, 4> ReMatIds;
1488 ReMatIds.resize(NumValNums, VirtRegMap::MAX_STACK_SLOT);
1489 BitVector ReMatDelete(NumValNums);
1490 unsigned Slot = VirtRegMap::MAX_STACK_SLOT;
1492 // Spilling a split live interval. It cannot be split any further. Also,
1493 // it's also guaranteed to be a single val# / range interval.
1494 if (vrm.getPreSplitReg(li.reg)) {
1495 vrm.setIsSplitFromReg(li.reg, 0);
1496 // Unset the split kill marker on the last use.
1497 unsigned KillIdx = vrm.getKillPoint(li.reg);
1499 MachineInstr *KillMI = getInstructionFromIndex(KillIdx);
1500 assert(KillMI && "Last use disappeared?");
1501 int KillOp = KillMI->findRegisterUseOperandIdx(li.reg, true);
1502 assert(KillOp != -1 && "Last use disappeared?");
1503 KillMI->getOperand(KillOp).setIsKill(false);
1505 vrm.removeKillPoint(li.reg);
1506 bool DefIsReMat = vrm.isReMaterialized(li.reg);
1507 Slot = vrm.getStackSlot(li.reg);
1508 assert(Slot != VirtRegMap::MAX_STACK_SLOT);
1509 MachineInstr *ReMatDefMI = DefIsReMat ?
1510 vrm.getReMaterializedMI(li.reg) : NULL;
1512 bool isLoadSS = DefIsReMat && tii_->isLoadFromStackSlot(ReMatDefMI, LdSlot);
1513 bool isLoad = isLoadSS ||
1514 (DefIsReMat && (ReMatDefMI->getDesc().isSimpleLoad()));
1515 bool IsFirstRange = true;
1516 for (LiveInterval::Ranges::const_iterator
1517 I = li.ranges.begin(), E = li.ranges.end(); I != E; ++I) {
1518 // If this is a split live interval with multiple ranges, it means there
1519 // are two-address instructions that re-defined the value. Only the
1520 // first def can be rematerialized!
1522 // Note ReMatOrigDefMI has already been deleted.
1523 rewriteInstructionsForSpills(li, false, I, NULL, ReMatDefMI,
1524 Slot, LdSlot, isLoad, isLoadSS, DefIsReMat,
1525 false, vrm, rc, ReMatIds, loopInfo,
1526 SpillMBBs, SpillIdxes, RestoreMBBs, RestoreIdxes,
1527 MBBVRegsMap, NewLIs, SSWeight);
1529 rewriteInstructionsForSpills(li, false, I, NULL, 0,
1530 Slot, 0, false, false, false,
1531 false, vrm, rc, ReMatIds, loopInfo,
1532 SpillMBBs, SpillIdxes, RestoreMBBs, RestoreIdxes,
1533 MBBVRegsMap, NewLIs, SSWeight);
1535 IsFirstRange = false;
1538 SSWeight = 0.0f; // Already accounted for when split.
1539 handleSpilledImpDefs(li, vrm, rc, NewLIs);
1543 bool TrySplit = SplitAtBB && !intervalIsInOneMBB(li);
1544 if (SplitLimit != -1 && (int)numSplits >= SplitLimit)
1548 bool NeedStackSlot = false;
1549 for (LiveInterval::const_vni_iterator i = li.vni_begin(), e = li.vni_end();
1551 const VNInfo *VNI = *i;
1552 unsigned VN = VNI->id;
1553 unsigned DefIdx = VNI->def;
1555 continue; // Dead val#.
1556 // Is the def for the val# rematerializable?
1557 MachineInstr *ReMatDefMI = (DefIdx == ~0u)
1558 ? 0 : getInstructionFromIndex(DefIdx);
1560 if (ReMatDefMI && isReMaterializable(li, VNI, ReMatDefMI, dummy)) {
1561 // Remember how to remat the def of this val#.
1562 ReMatOrigDefs[VN] = ReMatDefMI;
1563 // Original def may be modified so we have to make a copy here. vrm must
1565 ReMatDefs[VN] = ReMatDefMI = mf_->CloneMachineInstr(ReMatDefMI);
1567 bool CanDelete = true;
1568 if (VNI->hasPHIKill) {
1569 // A kill is a phi node, not all of its uses can be rematerialized.
1570 // It must not be deleted.
1572 // Need a stack slot if there is any live range where uses cannot be
1574 NeedStackSlot = true;
1577 ReMatDelete.set(VN);
1579 // Need a stack slot if there is any live range where uses cannot be
1581 NeedStackSlot = true;
1585 // One stack slot per live interval.
1586 if (NeedStackSlot && vrm.getPreSplitReg(li.reg) == 0)
1587 Slot = vrm.assignVirt2StackSlot(li.reg);
1589 // Create new intervals and rewrite defs and uses.
1590 for (LiveInterval::Ranges::const_iterator
1591 I = li.ranges.begin(), E = li.ranges.end(); I != E; ++I) {
1592 MachineInstr *ReMatDefMI = ReMatDefs[I->valno->id];
1593 MachineInstr *ReMatOrigDefMI = ReMatOrigDefs[I->valno->id];
1594 bool DefIsReMat = ReMatDefMI != NULL;
1595 bool CanDelete = ReMatDelete[I->valno->id];
1597 bool isLoadSS = DefIsReMat && tii_->isLoadFromStackSlot(ReMatDefMI, LdSlot);
1598 bool isLoad = isLoadSS ||
1599 (DefIsReMat && ReMatDefMI->getDesc().isSimpleLoad());
1600 rewriteInstructionsForSpills(li, TrySplit, I, ReMatOrigDefMI, ReMatDefMI,
1601 Slot, LdSlot, isLoad, isLoadSS, DefIsReMat,
1602 CanDelete, vrm, rc, ReMatIds, loopInfo,
1603 SpillMBBs, SpillIdxes, RestoreMBBs, RestoreIdxes,
1604 MBBVRegsMap, NewLIs, SSWeight);
1607 // Insert spills / restores if we are splitting.
1609 handleSpilledImpDefs(li, vrm, rc, NewLIs);
1613 SmallPtrSet<LiveInterval*, 4> AddedKill;
1614 SmallVector<unsigned, 2> Ops;
1615 if (NeedStackSlot) {
1616 int Id = SpillMBBs.find_first();
1618 MachineBasicBlock *MBB = mf_->getBlockNumbered(Id);
1619 unsigned loopDepth = loopInfo->getLoopDepth(MBB);
1620 std::vector<SRInfo> &spills = SpillIdxes[Id];
1621 for (unsigned i = 0, e = spills.size(); i != e; ++i) {
1622 int index = spills[i].index;
1623 unsigned VReg = spills[i].vreg;
1624 LiveInterval &nI = getOrCreateInterval(VReg);
1625 bool isReMat = vrm.isReMaterialized(VReg);
1626 MachineInstr *MI = getInstructionFromIndex(index);
1627 bool CanFold = false;
1628 bool FoundUse = false;
1630 if (spills[i].canFold) {
1632 for (unsigned j = 0, ee = MI->getNumOperands(); j != ee; ++j) {
1633 MachineOperand &MO = MI->getOperand(j);
1634 if (!MO.isRegister() || MO.getReg() != VReg)
1641 (!FoundUse && !alsoFoldARestore(Id, index, VReg,
1642 RestoreMBBs, RestoreIdxes))) {
1643 // MI has two-address uses of the same register. If the use
1644 // isn't the first and only use in the BB, then we can't fold
1645 // it. FIXME: Move this to rewriteInstructionsForSpills.
1652 // Fold the store into the def if possible.
1653 bool Folded = false;
1654 if (CanFold && !Ops.empty()) {
1655 if (tryFoldMemoryOperand(MI, vrm, NULL, index, Ops, true, Slot,VReg)){
1658 // Also folded uses, do not issue a load.
1659 eraseRestoreInfo(Id, index, VReg, RestoreMBBs, RestoreIdxes);
1660 nI.removeRange(getLoadIndex(index), getUseIndex(index)+1);
1662 nI.removeRange(getDefIndex(index), getStoreIndex(index));
1666 // Otherwise tell the spiller to issue a spill.
1668 LiveRange *LR = &nI.ranges[nI.ranges.size()-1];
1669 bool isKill = LR->end == getStoreIndex(index);
1670 if (!MI->registerDefIsDead(nI.reg))
1671 // No need to spill a dead def.
1672 vrm.addSpillPoint(VReg, isKill, MI);
1674 AddedKill.insert(&nI);
1677 // Update spill slot weight.
1679 SSWeight += getSpillWeight(true, false, loopDepth);
1681 Id = SpillMBBs.find_next(Id);
1685 int Id = RestoreMBBs.find_first();
1687 MachineBasicBlock *MBB = mf_->getBlockNumbered(Id);
1688 unsigned loopDepth = loopInfo->getLoopDepth(MBB);
1690 std::vector<SRInfo> &restores = RestoreIdxes[Id];
1691 for (unsigned i = 0, e = restores.size(); i != e; ++i) {
1692 int index = restores[i].index;
1695 unsigned VReg = restores[i].vreg;
1696 LiveInterval &nI = getOrCreateInterval(VReg);
1697 bool isReMat = vrm.isReMaterialized(VReg);
1698 MachineInstr *MI = getInstructionFromIndex(index);
1699 bool CanFold = false;
1701 if (restores[i].canFold) {
1703 for (unsigned j = 0, ee = MI->getNumOperands(); j != ee; ++j) {
1704 MachineOperand &MO = MI->getOperand(j);
1705 if (!MO.isRegister() || MO.getReg() != VReg)
1709 // If this restore were to be folded, it would have been folded
1718 // Fold the load into the use if possible.
1719 bool Folded = false;
1720 if (CanFold && !Ops.empty()) {
1722 Folded = tryFoldMemoryOperand(MI, vrm, NULL,index,Ops,true,Slot,VReg);
1724 MachineInstr *ReMatDefMI = vrm.getReMaterializedMI(VReg);
1726 bool isLoadSS = tii_->isLoadFromStackSlot(ReMatDefMI, LdSlot);
1727 // If the rematerializable def is a load, also try to fold it.
1728 if (isLoadSS || ReMatDefMI->getDesc().isSimpleLoad())
1729 Folded = tryFoldMemoryOperand(MI, vrm, ReMatDefMI, index,
1730 Ops, isLoadSS, LdSlot, VReg);
1731 unsigned ImpUse = getReMatImplicitUse(li, ReMatDefMI);
1733 // Re-matting an instruction with virtual register use. Add the
1734 // register as an implicit use on the use MI and update the register
1735 // interval's spill weight to HUGE_VALF to prevent it from being
1737 LiveInterval &ImpLi = getInterval(ImpUse);
1738 ImpLi.weight = HUGE_VALF;
1739 MI->addOperand(MachineOperand::CreateReg(ImpUse, false, true));
1743 // If folding is not possible / failed, then tell the spiller to issue a
1744 // load / rematerialization for us.
1746 nI.removeRange(getLoadIndex(index), getUseIndex(index)+1);
1748 vrm.addRestorePoint(VReg, MI);
1750 // Update spill slot weight.
1752 SSWeight += getSpillWeight(false, true, loopDepth);
1754 Id = RestoreMBBs.find_next(Id);
1757 // Finalize intervals: add kills, finalize spill weights, and filter out
1759 std::vector<LiveInterval*> RetNewLIs;
1760 for (unsigned i = 0, e = NewLIs.size(); i != e; ++i) {
1761 LiveInterval *LI = NewLIs[i];
1763 LI->weight /= LI->getSize();
1764 if (!AddedKill.count(LI)) {
1765 LiveRange *LR = &LI->ranges[LI->ranges.size()-1];
1766 unsigned LastUseIdx = getBaseIndex(LR->end);
1767 MachineInstr *LastUse = getInstructionFromIndex(LastUseIdx);
1768 int UseIdx = LastUse->findRegisterUseOperandIdx(LI->reg, false);
1769 assert(UseIdx != -1);
1770 if (LastUse->getOperand(UseIdx).isImplicit() ||
1771 LastUse->getDesc().getOperandConstraint(UseIdx,TOI::TIED_TO) == -1){
1772 LastUse->getOperand(UseIdx).setIsKill();
1773 vrm.addKillPoint(LI->reg, LastUseIdx);
1776 RetNewLIs.push_back(LI);
1780 handleSpilledImpDefs(li, vrm, rc, RetNewLIs);
1784 /// hasAllocatableSuperReg - Return true if the specified physical register has
1785 /// any super register that's allocatable.
1786 bool LiveIntervals::hasAllocatableSuperReg(unsigned Reg) const {
1787 for (const unsigned* AS = tri_->getSuperRegisters(Reg); *AS; ++AS)
1788 if (allocatableRegs_[*AS] && hasInterval(*AS))
1793 /// getRepresentativeReg - Find the largest super register of the specified
1794 /// physical register.
1795 unsigned LiveIntervals::getRepresentativeReg(unsigned Reg) const {
1796 // Find the largest super-register that is allocatable.
1797 unsigned BestReg = Reg;
1798 for (const unsigned* AS = tri_->getSuperRegisters(Reg); *AS; ++AS) {
1799 unsigned SuperReg = *AS;
1800 if (!hasAllocatableSuperReg(SuperReg) && hasInterval(SuperReg)) {
1808 /// getNumConflictsWithPhysReg - Return the number of uses and defs of the
1809 /// specified interval that conflicts with the specified physical register.
1810 unsigned LiveIntervals::getNumConflictsWithPhysReg(const LiveInterval &li,
1811 unsigned PhysReg) const {
1812 unsigned NumConflicts = 0;
1813 const LiveInterval &pli = getInterval(getRepresentativeReg(PhysReg));
1814 for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(li.reg),
1815 E = mri_->reg_end(); I != E; ++I) {
1816 MachineOperand &O = I.getOperand();
1817 MachineInstr *MI = O.getParent();
1818 unsigned Index = getInstructionIndex(MI);
1819 if (pli.liveAt(Index))
1822 return NumConflicts;
1825 /// spillPhysRegAroundRegDefsUses - Spill the specified physical register
1826 /// around all defs and uses of the specified interval.
1827 void LiveIntervals::spillPhysRegAroundRegDefsUses(const LiveInterval &li,
1828 unsigned PhysReg, VirtRegMap &vrm) {
1829 unsigned SpillReg = getRepresentativeReg(PhysReg);
1831 for (const unsigned *AS = tri_->getAliasSet(PhysReg); *AS; ++AS)
1832 // If there are registers which alias PhysReg, but which are not a
1833 // sub-register of the chosen representative super register. Assert
1834 // since we can't handle it yet.
1835 assert(*AS == SpillReg || !allocatableRegs_[*AS] ||
1836 tri_->isSuperRegister(*AS, SpillReg));
1838 LiveInterval &pli = getInterval(SpillReg);
1839 SmallPtrSet<MachineInstr*, 8> SeenMIs;
1840 for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(li.reg),
1841 E = mri_->reg_end(); I != E; ++I) {
1842 MachineOperand &O = I.getOperand();
1843 MachineInstr *MI = O.getParent();
1844 if (SeenMIs.count(MI))
1847 unsigned Index = getInstructionIndex(MI);
1848 if (pli.liveAt(Index)) {
1849 vrm.addEmergencySpill(SpillReg, MI);
1850 pli.removeRange(getLoadIndex(Index), getStoreIndex(Index)+1);
1851 for (const unsigned* AS = tri_->getSubRegisters(SpillReg); *AS; ++AS) {
1852 if (!hasInterval(*AS))
1854 LiveInterval &spli = getInterval(*AS);
1855 if (spli.liveAt(Index))
1856 spli.removeRange(getLoadIndex(Index), getStoreIndex(Index)+1);
1862 LiveRange LiveIntervals::addLiveRangeToEndOfBlock(unsigned reg,
1863 MachineInstr* startInst) {
1864 LiveInterval& Interval = getOrCreateInterval(reg);
1865 VNInfo* VN = Interval.getNextValue(
1866 getInstructionIndex(startInst) + InstrSlots::DEF,
1867 startInst, getVNInfoAllocator());
1868 VN->hasPHIKill = true;
1869 VN->kills.push_back(getMBBEndIdx(startInst->getParent()));
1870 LiveRange LR(getInstructionIndex(startInst) + InstrSlots::DEF,
1871 getMBBEndIdx(startInst->getParent()) + 1, VN);
1872 Interval.addRange(LR);